Membrane bioreactors are among the methods used for wastewater treatment nowadays. Because, the biomass concentration per unit area is high in those systems, different designs can be realized to decrease the pollutants such as nitrogen, phosphorus, bacteria and solid materials.
One of these designs is the pressure driven MBRs. The membrane including small pores is submerged into a tank filled with wastewater/sludge mixture and the permeate is separated from the wastewater/sludge mixture with the help of vacuum pressure applied to the system. The clogging of pores of membrane with time means that filtration of water will be more difficult. Therefore, filtration of water from wastewater/sludge mixture is no more possible without applying higher pressures.
Another solution offered to this problem is the osmotic membrane bioreactors (OMBRs) which do not require applying of pressure. In this method, more concentrated draw solution is circulated through the osmotic membrane which is found in a tank filled with wastewater/sludge mixture. The filtration part of treatment system is realized with the diffusion of water molecules into the membrane side with help of concentration difference. On the other hand, it has been seen that there are some problems by the operation of OMBRs such as low flux and concentration polarization.
Just because of these problems of decrease of treatment efficiency and operational difficulties, some solution offers have been developed.
In the known part of the art, it is mentioned about methods and devices for a recovering system of wastewater in the filed international patent document with application no: US2015360983A1 and date: Oct. 1, 2014 which includes osmotic membrane bioreactor, micropore membrane bioreactor nitrogen filtration system, high osmotic pressure solution and reconcentration processes required for efficient water recovery under low energy use.
In the known part of art, it is mentioned about an efficient recovery system for refinery wastewater in the filed Chinese patent document with application no: CN103771656 and date: Oct. 26, 2012 including sequential bath reactor and osmotic membrane bioreactor.
In the known part of art, it is mentioned about manufacturing of tubular nanofiber membrane via coating nanofiber layer on a hallow braided rope and manufacturing of forward osmosis membrane via coating of thin film composite layer on tubular nanofiber membrane used as support layer, in the filed Turkish patent document with application no: TR201514718 and date: Nov. 23, 2015.
The reason of the low flux which is one of the related problems seen in OMBRs, is the insufficiency of osmotic pressure depended on the membrane structure. Another problem is the salt accumulation in the reactor and the reason of it is the salt flux from the side of draw solution circulated through the membrane into the reactor and also increasing of this salt concentration in the reactor as a result of water flux from the reactor into the membrane. On the other hand, the most important problems by pressure driven membranes are clogging problem and low discharge water quality.
To overcome these problems related with MBRs and OMBRs mentioned above, the need of realization of new operation methods with some solution offers has been appeared.